Selector vs MultiSelector. Which to inherit from?

I'm trying to make a something like a diagram designer. I want it to have a ItemsSource, so it will be a ItemsControl, but I don't know which class to choose as my base class.

I see that Selector can have multiple selected items, but I think MultiSelector has a too evident name! 

Which one is better for a diagram designer? 

And one last question, how could a child autoselect itself, for example, under mouse clicks?

Thanks.

Desde España / From Spain